The present invention relates generally to communication systems, and more particularly to a method and apparatus for backhaul in a communication system.
Cellular communication systems provide for communication between remote units and cellular base stations. Cellular communication systems allow for a remote unit to transfer processing from one base station to another. This process of transferring processing of a call is commonly referred to as handoff.
There are two types of handoff in cellular communication systems. Hard handoff refers to a process wherein processing of a call is transferred from a first base station to a second base station that is better able to process the call. Soft handoff refers to a process wherein a remote unit is simultaneously communicating with several base stations. Each base station receives the communication signal from the remote unit. The base station receivers demodulate the signal received from the remote unit, and send the demodulated data to a selection unit after demodulation. The selection unit then selects the best frame of those sent to it based upon a quality metric associated with each frame. The base stations in communication with the remote unit backhaul that remote unit""s demodulated data to a selection unit that selects the best frame, based upon the quality metric, received from the base stations in communication with the remote unit.
A major cost for cellular operators is that for backhaul connection expense. As used herein, backhaul refers to transporting data between communication infrastructure equipment. Whether the backhaul connections consist of T1 connections, copper cables, fiber optic cables, coaxial cables, microwave links, or other connections, the cost associated with the backhaul connections between infrastructure equipment is sizable.
During periods when a remote unit is in communication with multiple base stations, such as during soft handoff, a frame is sent by the remote unit and received by all base stations involved in the soft handoff communication. In current communication systems, each of these base stations will demodulate the data and send, or backhaul, the data to other cellular infrastructure equipment. Each base station that backhauls this data is taking up precious bandwidth in the system. In addition, even though multiple base stations are receiving, demodulating, and backhauling the data, only one copy of the data will be used by he cellular infrastructure equipment. The other data is discarded after being expensively backhauled.
Consequently, a need exists for a method and apparatus for backhauling data within a communication system that is less costly and more efficient than prior art methods of backhauling data.